Fire extinguisher



Patented Dec. 8, 1 936 UNITED STATES PATENT OFFICE FIRE EXTINGUISHER No Drawing. Application Aprifio, 1928, Serial No. 269,018

8 Claims;

This invention relates to the extinguishing of fires.

It is among the objects of this invention to provide a: fire-extinguisher charge which has superior fire-extinguishing properties, and sumcient to meet the present requirements for such extinguishers; and this invention is in the nature of a discovery disclosing particular compounds which involve a certain group of elements which compounds we have found to possess unusual or special advantages from the fire-extinguishing standpoint.

Another object of this invention is to provide a novel method of extinguishing fires which is highly eifective for extinguishing both wood and oil fires.

Other objects and advantages of this invention will be apparent from the following disclosure. Combustion or active burning is a chemical reaction, and obeys the general laws governing such reactions. Ordinary fire is combustion out of control. The method of fire extinguishing heretofore used involves either the cooling of the burning material below its kindling point, or the smothering of the fire by the exclusion of air or oxygen from the combustion zone.

The present invention provides a novel method of extinguishing fires which is highly effective and superior to the methods heretofore used. This method involves the introduction upon the fire of a compound which has what may be termed a high negative-catalytic effect upon combustion. This effect tends to inhibit combustion, or the tendency of the materials to react, as distinguished from a cooling or smothering effect. We have discovered that certain compounds involving a certain group of elements possess this negativecatalytic eifect, and provide superior fire-extinguishing mediums. In detail, we have discovered that those alkali metal elements which are contained in group I of the Cir periodic table of elements, namely lithium, so-

istics referred to, some of the metals of this group are superior to others. For example, those having the heavier atomic weights have a general superiority over those having the lighter atomic weights. Specifically we have found that potassium, rubidium and caesium when combined with a radical referred to, have relatively the more pronounced fire-extinguishing effect; whereas sodium and lithium have a poorer efiect.

Reference is herein made to the copending application of Charles A. Thomas and Carroll A. Hochwalt, Serial No. 257,400, filed February 27, 1928, now Patent 1,895,530, in which are disclosed compounds of alkali metal elements of group I of the periodic table having exceptional or superior fire-extinguishing characteristics. These compounds are applicable for use in carrying out the method of the present invention.

We have also discovered that the negativecataly'tic eifect upon combustion or the exceptional fire-extinguishing effect of these compounds is superior within a certain temperature range, which range may vary somewhat for difi'erent compounds. We have found, for example, that the negative-catalytic effect in general is superior within a temperature range of C. to 325 C. In testing these various compounds, dilute water solutions of the compounds were prepared in order to determine the lowest concentration of a solution which would put out a standard test fire. It was at these low concentrations that the temperature efiect was noticeable. The standard test fire was generally prepared by igniting gasoline contained within a small pan, and the extinguishing effect of the various compounds determined by projecting various concentrations of these compounds upon the oil fire to determine the lowest concentration which would put out this standard test fire. The temperature of the side of the pan above the gasoline level was determined by a potentiometer. It was found that when such dilute solutions were projected on a fire where the temperature of the wall of the pan was above the range specified, the temperature first dropped to within the effective temperature range and then the fire would go out.

From the results obtained with the test fire, it is believed that the extinguishing action of such a solution upon an actively burning fire where the temperature is higher than the range above specified, is substantially as follows. First there is a lowering of the temperat re Of the combustion to the highly effective temperature I range of the fire-extinguishing compound, where the compound then exhibits its strongest negative-catalytic effect upon combustion to extinguish the fire.

For accurately comparing the fire-extinguishing effects of various compounds in very dilute water solutions an average temperature of the wall of the test pan of 270 C. gave very satisfactory results.

Where there is a high concentration of a compound of an alkali metal having superior fireextinguishing properties in the solution, the fire is extinguished under all conditions. In general, it may be said that the fire-extinguishing properties of a water solution of any one of these superior fire-extinguishing compounds mentioned above increases with the concentration of the solution up to a point of high concentration. In actual fire-extinguishing practice, it is desirable to have the fire-extinguishing solutions sufiicientlyconcentrated to get the best extinguishing effects, such for example as a concentration'jin'excess of 15% by'weight of the ":compound. High solubility of a compound is an. advantage, for this permits a high concentration of the alkali metal compound to be placed in the solution withincreased extinguishfing effect. Actual tests have shown that sufiic'iently concentrated water solutions of these compounds above mentioned havingi superior fire-extinguishing properties, and particularly water solutions of compounds of potassium, ru-

bidium and caesium, provide extinguishing mediums which are as effective on oil fires as carbon tetrachloride, and which unlike carbon tetrachloride do not give off obnoxious fumes when used on the fire; and. at the same time these solutions are also applicable to general fires or wood fires'and are more efiective on such wood fires than any extinguisher charge heretofore known.

" in the extinguishing of 011 tank fires, the best 'results are obtained by projecting a solution of a compound of an alkali metal element having high fire-extinguishing.properties across and above the seat. of combustion in a manner to impinge the solution 'upon the far inner wall of most efiective.

i 'We have further found that of the inorganic c mpounds, in general the oxidizing compounds V of the alkali metal elements are superior and 'providehighly efiective fire-extinguishing mediums, Thus, a compound comprising an alkali metal element of group Icombined with a chromate radical or a .dichromate radical, such as sodium dichromate or potassium dichromate, provides a superior fire-extinguishing agent. We havealso. discovered that when these ele- V, ments arelcombinedwith other oxidizing radigals such as the permanganate -radical,.superior fire-extinguishing" compounds, such as potassium permanganate for-example, are provided.

Itis also true,.according to ourdiscovery; that inaddition' to the oxidizing compounds mentioned, other oxidizing compounds such as those involving radicals containing a halogen and oxy- -are highly effective -fire-extinguishing percentage of oxygen in the molecule is also exemplified in certain organic compounds. For example, potassium tartrate is found to be an excellent fire-extinguishing medium; but the bitartrate of potassium is found to be even superior to the tartrate of potassium, both being organic compounds of an alkali metal element of group I and having superior fire-extinguishing properties.

We have also discovered by these investigations, that these alkali metal elements above mentioned combined with an aromatic organic radical provide compounds having superior fireextinguishing properties. Thus, a compound having an aromatic carboxylic acid radical, such as the gallate which is an aromatic trioxymonocarboxylic acid radical, has these exceptional fire-extinguishing properties when combined with an alkali metal element such as potassium.

It has also been found that amino compounds of these alkali metals, such as potassium anthranilate which is an aromatic amidomonocarboxylic acid radical, have these superior fireextinguishing properties.

In referring above and in the claims to the superior or exceptional fire-extinguishing characteristics of these various substances, we mean in comparison with the present-day requirements and conditions which have to be met in the specified tests outlined by Underwriters Laboratories. An example of such a requirement or test is what is termed the partition test fire. The partition used in this test comprises a wooden decking 10' square made of tongue and groove pine flooring, onto which is nailed four layers of 1"x1" dressed spruce strips 10' long. In the first layer, the strips are placed 12" apart. The second layer runing at right angles to the first layer has the strips 1" apart. The third layer running at right angles to the second layer has the strips 12 apart. The fourth layer running at right angles to the third layer has the strips 1" apart. This completed partition sample has five gallons of fuel oil evenly sprinkled over the lattice work surface. The sample is then fastened in a vertical position, and a quantity of excelsior is placed along the lower edge and ignited. At regular intervals three additional supplies of excelsior are pushed up to feed the fire. After the fire has burned five or six minutes, or until some of the strips begin to break, the extinguisher is applied. The time for extinguishment is taken at the time all flame disappears. Using a. ten quart conventional soda and acid charge, this fire generally requires on an average about thirty-five seconds to be extinguished,almost invariably over twenty-five seconds. Conventional types and sizes of carbon tetrachloride extinguishers are found to be totally inefiectlve on this type of test fire. However, using only seven quarts of a Water solution containing a relatively high concentration, such as in excess of 15% by weight, of an alkali metal compound having the exceptional fire extinguishing properties of the present invention, the solution exhibiting the unusual negative catalytic efiect upon combustion characteristic of the mediums of the present invention, this standard partition test fire is readily extinguished in considerably less than twenty-five seconds, often in as short a time as nine to ten seconds.

While the materials and compositions herein described constitute preferred embodiments of our invention, it is to be understood that the invention is not limited to these precise materials and compositions, and that changes may be made without departing from the scope of our invention as defined in the appended claims.

What is claimed is:

1. The method of extinguishing oil tank fires which comprises projecting an aqueous solution of high concentration of a compound of an alkali metal element of group I of the periodic table of elements having high fire-extinguishing properties, across and above the seat of combustion in a manner to impinge the solution upon the far inner wall of the tank, whereby a fine spray of the solution is produced above the seat of combustion.

2. The method of extinguishing an oil tank fire which comprises projecting a relatively concentrated aqueous solution of a compound of potassium having inherently exceptional fire extinguishing properties in the form of a fine spray immediately above the seat of combustion of the tank fire, the solution having a highly effective negative catalytic effect upon combustion, and being capable of extinguishing a standard partition test fire, when applied in the usual test quantities or less, in less than twentyfive seconds.

3. The method in the extinguishing of fire, which comprises projecting upon the fire a solution of an alkali metal salt of an amide-carboxylic acid.

4. The method in the extinguishing of fire, which comprises projecting upon the fire a water solution of an alkali metal salt of an aromatic amido-carboxylic acid. W

5. The method in the extinguishing of fire, which comprises projecting upon the fire a water solution of potassium anthranilate.

6. The method in the extinguishing of fire, which comprises projecting upon the fire a solution of high concentration of an amino compound of am alkali metal element, the solution characterized by a negative catalytic efiect upon combustion.

'7. The method in the extinguishing of fire, which comprises projecting upon the fire a solution of a compound of an alkali metal element combined with an anthranilate radical.

8. The method in the extinguishing of fire, which comprises projecting upon the fire a solution of an alkali metal gallate.

CHARLES A. THOMAS. CARROLL A. HOCHWALT. 

